具體實現過程：

    process = Runtime.getRuntime().exec("su");
   dos = new DataOutputStream(process.getOutputStream());
   //開啟gpio引腳74，即status_led連線的引腳
   dos.writeBytes("echo 74 > /sys/class/gpio/export"+"\n");
   
   dos.flush(); 
   //設定引腳功能為輸出
   dos.writeBytes("echo out > /sys/class/gpio/gpio74/direction"+"\n");
   dos.flush(); 

   
   dos.close();

//led開：

private void cmdLedOn() {
  // TODO Auto-generated method stub
  DataOutputStream dos = null;
  
  
  try {
   process = Runtime.getRuntime().exec("su");
   dos = new DataOutputStream(process.getOutputStream());
   dos.writeBytes("echo 1 > /sys/class/gpio/gpio74/value"+"\n");
   
   dos.flush();
   dos.close();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } 
  
 }

//led關

private void cmdLedOff() {
  // TODO Auto-generated method stub
  DataOutputStream dos = null;
  
  try {
   process = Runtime.getRuntime().exec("su");
   dos = new DataOutputStream(process.getOutputStream());
   dos.writeBytes("echo 0 > /sys/class/gpio/gpio74/value"+"\n");
   
   dos.flush();
   dos.close();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } 
 }